[Zeke]

I read the OP a few time to make sure I didn't miss anything. So far, Higgins has the best insight and fairest assessment of the situation. But no solution as to what to do about the lack of control over the maintenance guy's MO.

Some changes in this guy's MO would be in order. Thing is, from what I read, he is going to be highly resistant to any change. I would do 2 things: explain in no uncertain terms why any changes are going to take place, and make those changes slight and a little at a time until you are satisfied that this employee is benevolent for your company.

Total objectivity is paramount here. Forget about hearsay. I would also ask the maintenance guy for suggestions as a way to get him vested in your objectives. And remember your position at all times. Sometimes you have authority over subordinates but you don't have seniority.